Mokele Mbembe, Vavra Defense

The Vavra Defense is Black's answer to the threat behind 3. d4 in the Mokele Mbembe. White wants to play f3 and trap the knight on e4. By playing 3...e6, Black opens the d8–h4 diagonal, so 4. f3? runs into 4...Qh4+ 5. g3 Nxg3. The knight capture works because the h2-pawn is pinned against the rook on h1. The idea saves the knight but does not cure its exposed position, and engines consider White's advantage large.

The critical reply is 4. Nh3, which covers g5 and f4 and starts a race for the g5-square. After 4...d5 5. f3 Qh4+? 6. g3 Nxg3 7. Bg5, the bishop hits the queen with the knight's protection, and after 7...Qh5 8. hxg3 the trick has failed. A sturdier try is 4...h6 5. Qg4 d5 6. f3 Ng5 7. Nxg5 hxg5 8. Bxg5 f6. In practice, the natural 4. Bd3 is White's most frequent choice, followed by 4. Nf3. The tempting 4. f3 is played often, but Black outscores White after it.